Urinary sediment findings and clinicopathologic features of IgA nephropathy patients with acute kidney injury / 中华肾脏病杂志

ABSTRACT

Objective:To investigate the urinary sediment findings and the clinicopathologic features of IgA nephropathy (IgAN) patients with acute kidney injury (AKI).Methods:It was a retrospective study. The patients with renal biopsy-proven primary IgAN in Peking University First Hospital from January 31, 2013 to July 31, 2015 were selected. According to whether AKI occurred at renal biopsy or not, the patients were divided into AKI group and non-AKI group. Morning urine samples were obtained on the day of renal biopsy. Urine sediments, including various cells and casts, were examined. The clinical data, urinary sediments, and renal pathological changes were compared between the two groups. Logistic regression analysis was performed to identify the association between clinical pathological changes, urinary sediment indicators and AKI, or clinical pathological changes and urinary sediment indicators.Results:There were 502 IgAN patients enrolled in this study, with age of (36.1±12.1) years old and 261 males (52.0%). The incidence of AKI was 11.4% (57/502) among the enrolled patients at the time of renal biopsy. Common causes of AKI included gross hematuria-induced AKI (10 cases), acute tubulointerstitial nephritis (10 cases), crescentic IgAN (9 cases), malignant hypertensive renal damage (6 cases), and multiple etioloqy or unknown etiology (22 cases). Compared with non-AKI group, AKI group had higher proportions of males and malignant hypertension, higher levels of proteinuria and urinary erythrocyte counts, and higher frequencies of gross hematuria, leukocyturia, renal tubular epithelial cells, and granular casts (all P<0.05). AKI group also had higher proportions of severe tubular atrophy/interstitial fibrosis (T2) and cellular/cellular fibrous crescent formation (C2) than non-AKI group (both P<0.05). Logistic regression analysis results showed that, there were statistically significant differences in the correlation between AKI and gender, 24 h urinary protein, urinary erythrocyte counts, granular casts and renal tubular atrophy/interstitial fibrosis (T) scores (all P<0.05). Hematuria, leukocyturia, red blood cell casts, white blood cell casts, granular casts, and fatty casts were correlated with endothelial hypercellularity (E) and cellular/cellular fibrous crescent formation (C) scores, respectively (all P<0.05). Hematuria was correlated with mesangial hypercellularity (M) scores ( OR=2.613, 95% CI 1.520-4.493, P=0.001). Hematuria ( OR=1.723, 95% CI 1.017-2.919, P=0.043) and fatty casts ( OR=2.646, 95% CI 1.122-6.238, P=0.026) were correlated with segmental sclerosis or adhesion (S) scores. Leukocyturia ( OR=1.645, 95% CI 1.154-2.347, P=0.006) and fatty casts ( OR=2.344, 95% CI 1.202-4.572, P=0.012) were correlated with T scores. Epithelial cell cast was correlated with C scores ( OR=1.857, 95% CI 1.174-2.939, P=0.008). Conclusions:AKI is a common complication among IgAN patients with diverse etiology and more severe clinicopathological features. Urinary sediment findings can reflect renal pathological changes to some extent, and therefore assist in the clinical diagnosis and treatment of IgAN patients with AKI.